The penetration rate of a downhole drilling tool may be increased by increasing or "intensifying" the circulation pressure of the drilling mud as it exits the drill bit. Although prior art intensifiers were found to increase penetration rates and tool effectiveness, the design of intensifiers is limited by practical considerations such as mud pump restrictions and drill pipe degradation. Mud surface pressures in excess of 6000 psi prohibitively increase the cost of wear on surface equipment beyond the cost savings generated by the enhanced penetration.
One type of prior art intensifier elevates the pressure of a small percentage of the circulating mud by using the inner string of a dual drill pipe as a high pressure conduit to the bit. As with other prior art designs, the cost savings generated by the penetration rate increase did not justify the total cost burden placed on the drilling operation. A more efficient mud pressure intensifier design is needed.